Women in all economic, social, and cultural circumstances suffer from high rates of unplanned pregnancy, along with a high prevalence and incidence of sexually transmitted diseases. Trends in the United States and lesser developed economies are going in the wrong direction. The availability of a single multipurpose prevention product (MPT) that prevents both unplanned pregnancy and one or more of the most prevalent sexually transmitted diseases is a priority for both NICHD and NIAID. The development of Yaso-GEL, a vaginal gel formulation, will provide one of the first MPT products offering both pregnancy and STI protection, one that is easy to obtain and to use, that does not require medical services. In addition, Yaso-GEL is applied vaginally pre-coitally, has pre-fertilization contraceptive action, is non-hormonal and non-systemic. These characteristics avoid many safety concerns of current contraceptive users. The primary purpose of this Phase 2B grant is to complete CMC and toxicology studies required by FDA to submit an IND for Yaso-GEL. Secondarily, based on in vitro data, we wish to study the prophylactic potential of Yaso-GEL against two common sexually transmitted infections in cutting edge murine models. We are developing a new drug, polyphenylene carboxymethylene (PPCM) in a vaginal contraceptive gel (Yaso-GEL) as a multipurpose prevention technology (MPT) under R44HD092206. In preclinical testing, PPCM inhibits a broad spectrum of sexually transmitted infections (STIs) including Neisseria gonorrhoeae (Ng), Chlamydia trachomatis (Ct), Herpes simplex virus (HSV) and human immunodeficiency virus (HIV), in addition to having contraceptive activity. Under this grant, we will complete the work needed to open our IND. This includes: a) scale up Yaso- GEL under cGMP, fill applicators for clinical trials and establish a 3-year stability study; b) complete a toxicology study in rats as a second species; c) complete the last genotoxicity study; d) validate the bioassay in human cervicovaginal secretions and plasma; e) design Phase I and Phase 2 clinical trials for safety and contraceptive efficacy, utilizing a new ex vivo assay of contraceptive activity to establish optimal dose response; f) submit the IND. Secondarily, Yaso-GEL will be evaluated in murine models for prevention of infection with Neisseria gonorrhoeae (Ng) and Chlamydia trachomatis (Ct). If effective, future clinical trials may be conducted to evaluate prevention of these important STI pathogens in humans.